FBI agents fanned out across Cook County on Thursday with grand jury subpoenas and a search warrant, probing deep into the role clout plays in county hiring.

The investigation, quietly under way since late last year, burst dramatically into public view Thursday morning. The flurry of activity indicated that federal prosecutors are now taking a hard look at clout and hiring in Cook County, even as they are investigating state hiring by the Blagojevich administration and city hiring by the Daley administration.

More than a dozen agents descended on the County Building around 9 a.m. Thursday to search the county's human resources bureau, where hiring and personnel records are kept. Agents remained all day in the 8th floor office at 118 N. Clark St.

In addition to the search warrant, agents delivered subpoenas for documents related to hiring at departments throughout the county. Subpoenas went to county health facilities, the Highway Department and the Cook County Forest Preserve District.

In a statement, Cook County Board President Bobbie Steele said the county would cooperate fully in responding to subpoenas delivered to various departments. Steele also said the human resources bureau was cooperating with the execution of the search warrant.

"I am committed to doing what is necessary to root out any problems," Steele's statement said. Steele assumed the office Aug. 1, replacing John Stroger, who had suffered a stroke.

The subpoenas seek documents related to "non-exempt" jobs, Steele said. Under a court order known as the Shakman decree, those positions are supposed to be filled on the basis of qualifications, not political influence.

Mayor Richard Daley's patronage chief, Robert Sorich, and three other former city officials were convicted of committing fraud and other crimes to circumvent the decades-old Shakman decree, which first applied to the City of Chicago and later to Cook County.

The federal investigation into the city's hiring is still under way.

Prosecutors are also engaged in a broad probe of hiring under Gov. Rod Blagojevich, who has acknowledged being interviewed by federal authorities.

In June, U.S. Atty. Patrick Fitzgerald sent a letter to Illinois Atty. Gen. Lisa Madigan saying his office has developed a number of credible witnesses in its investigation of allegations of "endemic hiring fraud" in multiple state agencies.

Though Thursday was the first public indication that the federal government is investigating hiring practices in Cook County, sources familiar with the investigation said the probe got under way in late 2005.

The sources said the search warrant was issued specifically for the human resources bureau because that is an area where records are concentrated.

The affidavit outlining the reason for seeking the search warrant is under seal.

Cheryl Cato, spokeswoman for the county's health bureau, said agents visited a number of its facilities early Thursday, including Stroger, Provident, Oak Forest and Cermak Hospitals.

"I don't know if they've taken anything," Cato said.

The flurry of activity on Thursday came about two weeks after Steele placed Gerald Nichols, who had been Stroger's patronage chief, on paid suspension.

Steele's actions followed a Chicago Sun-Times article in which a county highway supervisor claimed Nichols pressured him to hire a political ally of Stroger's.

The government's investigation quickly became an issue in the Nov. 7 election for County Board president.

"Clearly this is just the tip of the iceberg," Peraica said. "There's a criminal conspiracy here that has been going on for quite some time to falsify job applications, to alter test scores, to hire unqualified individuals, principally from the 8th Ward."

Todd Stroger suggested the federal activity was linked to a motion filed by Michael Shakman, the lawyer whose lawsuit led to the Shakman decree. Shakman returned to federal court in recent weeks to request the appointment of a federal monitor to oversee county hiring.

Stroger said he was not surprised by the investigation, and he added, "I don't think it's a surprise to many people. And I don't know what they are looking for or what they will find."

Stroger sought to distance himself from the federal probe.

"That's my father's administration," said Stroger, who was speaking at a news conference on an unrelated matter when the news broke of the federal search. "At this point, I am a city councilman and that is the job I've been doing."

County Commissioner Forrest Claypool, who lost to John Stroger in the March Democratic primary, said he was not surprised that the federal government is now probing hiring at the county.